Dual orifice fuel nozzle with air-assisted primary at low flow rates

ABSTRACT

A dual orifice liquid fuel nozzle for a combustion chamber including a pressure responsive valve to help produce smaller fuel droplets at lower fuel flow for more consistent combustion. The device comprises a valve housing having a coaxial fuel inlet, an inlet for a gas such as air, a spring-loaded movable valve telescopically mounted on the fuel inlet and a secondary passage. At low pressure fuel flow the movable valve permits the gas to contact the fuel so as to atomize it. When fuel pressure increases, the valve shuts off the gas, while permitting additional liquid fuel to enter the secondary passage.

United States Patent [1 1 [111 3,785,570 Krieger 1 Jan. 15, 1974 [54] DUAL ORIFICE FUEL NOZZLE WITH 2,954,172 9/1960 Grundman 239/464 x I S S E PRIMARY AT LOW FLOW 2,969,924 1/1961 Jay 239/440 X RATES 3,443,760 5/1969 Simmons 239/410 [75] Inventor: Stanley Krieger, Rivera Beach, Fla. Primary Examiner M Henson wood, Jr [73] Assignee: The United States of America as Assistant Examiner.1ohn J. Love represented by the Secretary of the Att0rneyl-larry M. Saragovitz et a1, Army, Washington, D.C, [22] Filed: Aug. 30, 1972 [57] ABSTRACT [21] Appl. No.: 284,847

A dual orifice liquid fuel nozzle for a combustion chamber including a pressure responsive valve to help produce smaller fuel droplets at lower fuel flow for more consistent combustion. The device comprises a valve housing having a coaxial fuel inlet, an inlet for a gas such as-air, a spring-loaded movable valve telescopically mounted on the fuel inlet and a secondary passage. At low pressure fuel flow the movable valve permits the gas to contact the fuel so as to atomize it.

[56] References. Cited When fuel pressure increases, the valve shuts off the gas, while permitting additional liquid fuel to enter the UNITED STATES PATENTS Secondary passage 2,588,485 3/1952 Clarke et al. 239/464 3,520,480 7/1970 Halvorsen 239/404 7 Claims, 3 Drawing Figures DUAL ORIFICE FUEL NOZZLE WITH AIR-ASSISTED PRIMARY AT LOW FLOW RATES The present invention relates to a dual orifice liquid fuel nozzle for a combustion chamber and more particularly to a nozzle having a valve to admit air or other gas at low fuel pressure to atomize the liquid fuel, and to shut off the air at high fuel pressure while admitting additional liquid fuel.

In combustion chambers, as for instance, in a gas turbine, etc., it is necessary to atomize (disperse into small droplets) the liquid fuel entering the combustion chamber so as to facilitate combustion. This must take place at low as well as at increased fuel flow pressures to assure that the combustion is as nearly complete as possible. A properly designed conventional liquid fuel injection nozzle will deliver the desired atomized liquid fuel spray at high fuel flow pressures; however, such a nozzle tends to be grossly inefficient at low fuel flow pressures. Conversely, a liquid fuel injection nozzle conventionally designed to deliver an atomized spray at low fuel flow pressure by the admission of atomizing air or other gas, is unable to operate satisfactorily at high fuel flow pressures.

The present invention overcomes these disadvantages by providing a liquid fuel injection nozzle with a valve of simple construction, preferably of the springloaded type, which is capableof admitting atomizing air (or other gas) when the fuel flow pressure increases, while admitting additional liquid fuel at such increased fuel flow pressure. Theatomizing performance of the new valve is further improved by the provision of means for swirling the liquid fuel during its passage throught the nozzle.

These and other objects and advantages of the present invention will be fully apparent from the following description when taken in connection with the annexed drawing, in which:

FIG. 1 is an axial section of the nozzle of this invention and illustrating the valve as in the gas admitting position at low fuel pressure;

FIG. 2 is asimilar view showing the valve as closing the gas port upon increasing fuel pressure, and the combustion wall portion 2 being omitted;

FIG. 3 is a similar view showing the valve in position when the liquid fuel feed is at full pressure, the secondary passage being used. A

Referring in detail to the drawing, reference character 1 indicates generally the fuel nozzle of this invention. Nozzle 1 comprises a tubular valve body 3 having a reduced nozzle portion 4 which is mounted in the wall of combustion chamber 2, a portion of which is shown in FIG 1. Body 3 is closed at its bottom by a closure member 5 which is detachably secured thereto. Closure member 5 is provided with an axially disposed liquid fuel inlet 6 extending into a chamber 7 formed in body 3. Body 3 is provided with an axial bore 8 and a counterbore 9 disposed adjacent chamber 7 to provide a passage between chamber 7 and the combustion chamber. A beveled valve seat 10 is formed by bores 8 and 9. A tubular valve 11 is telescopically mounted on that portion of inlet 6 extending into chamber 7. Valve 11 also has a reduced upper portion 12 to form a beveled surface 13 for mating with valve seat 10 when the valve lll is in closed position. A flange 14 is carried by the lower end of valve 11 to provide a'retainer for a coil spring 15 encircling valve 11 and biasing against a thickened portion 16 formed in body 3 and flange l4.

Thickened portion 16 is provided with a radially disposed air inlet 17 communicating with bore 8. A secondary passageway 18 provides communication between chamber 7 and bores 8 and 9. Fuel inlet 6 is provided with radial fuel ports 19 in its portion extending into chamber 7. Since the diameter of the nozzle portion 12 of valve 11 is less than the diameter of bores 8 and 9, a

an annular space is provided between the nozzle portions 12 and 4 as shown, for admission of air from inlet 17, or for fuel from secondary passageway 18 from chamber 7. Swirl vanes 20 are provided in the primary fuel passageway for creating fuel turbulence, as shown. The swirling motion thus imparted to the liquid fuel aids in the atomization when entering the combustion chamber.

The arrangement of nozzle 1 provides a primary fuel passage through inlet 6 and valve 11 and a secondary fuel passage through bores 19 in inlet 6, chamber 7, passageway 18, and the annular space between 12 and 4. The secondary passage 18 and the passages contiguous thereto are preferably so dimensioned that liquid duel passing therethrough is also swirled.

The operation of the nozzle is simple and automatic. In FIG. 1, the valve is shown in'the position for low fuel pressure, valve 11 being held by spring 15 in a first position so that inlet 17 is open to permit air or other gas to contact the liquid fuel and atomize it when it emerges from the primary fuel passageway into the combustion chamber 2. As the fuel pressure increases, see FIG. 2, valve 11 is forced towards a second position to shut off air inlet 17. Upon reaching full fuel pressure, valve 11 seats in a fully closed position, see FIG. 3, to open radial bores 19 in inlet 6 so that additional liquid fuel can enter chamber 7 and flow through secondary passageway 18 in a swirling (tangential) path, to be atomized in combustion chamber 2.

As the fuel flow pressure drops across the nozzle, valve 111 will return to its first position again to admit air or other gas through inlet 17.-

Combustion air is supplied to combustion chamber 2 through a conventional valve or inlet (not shown) separate from nozzle 1. The air admitted to combustion chamber 2 through nozzle 1 at low fuel flow pressures also takes part in the combustion process; this, however, is incidental. The principal function of the air passing through nozzle 1 at low fuel flow pressure is to atomize the liquid fuel as it enters combustion chamber 2. Other gases can be substituted for air in nozzle 1, if desired.

The foregoing description of a preferred embodiment of my invention is intended to be illustrative rather then in a limiting sense.

I claim:

1. A tubular liquid fuel nozzle having a tubular primary fuel passageway mounted in coaxial arrangement in said fuel nozzle, a tubular valve telescopically mounted on the inner portion of said tubular primary fuel passageway and movable by fuel flow pressure between a first position at low fuel flow pressure and a second position at increased fuel flow pressure, said valve having a reduced inner portion of smaller diameter than the inside diameter of said reduced portion of said fuel nozzle whereby a secondary passageway is formed, and a gas inlet leading to said secondary passageway;

said secondary passageway being open to said gas inlet by said valve when said valve is in said first position at low fuel flow pressure whereby liquid fuel emerging from said primary passageway is atomized by contact with said gas emerging from said secondary passageway; and I said secondary passageway being closed to said gas inlet but open to the-passage of additional liquid fuel by said valve when said valve is in said second position at increased fuel flow pressure.

2. A nozzle according to claim 1, including means for swirling liquid fuel passing through said primary passageway.

3. A nozzle according to claim 1, including means for swirling liquid fuel passing through said secondary pasa reduced inner portion adapted to be mounted in the burner wall of a combustion chamber. 

1. A tubular liquid fuel nozzle having a tubular primary fuel passageway mounted in coaxial arrangement in said fuel nozzle, a tubular valve telescopically mounted on the inner portion of said tubular primary fuel passageway and movable by fuel flow pressure between a first position at low fuel flow pressure and a second position at increased fuel flow pressure, said valve having a reduced inner portion of smaller diameter than the inside diameter of said reduced portion of said fuel nozzle whereby a secondary passageway is formed, and a gas inlet leading to said secondary passageway; said secondary passageway being open to said gas inlet by said valve when said valve is in said first position at low fuel flow pressure whereby liquid fuel emerging from said primary passageway is atomized by contact with said gas emerging from said secondary passageway; and said secondary passageway being closed to said gas inlet but open to the passage of additional liquid fuel by said valve when said valve is in said second position at increased fuel flow pressure.
 2. A nozzle according to claim 1, including means for swirling liquid fuel passing through said primary passageway.
 3. A nozzle according to claim 1, including means for swirling liquid fuel passing through said secondary passageway.
 4. A nozzle according to claim 1, including means for swirling liquid fuel passing through said primary and secondary passageways.
 5. A nozzle according to claim 1, wherein said gas is air.
 6. A nozzle according to claim 1, wherein said valve is spring-loaded.
 7. A nozzle according to claim 1, said nozzle having a reduced inner portion adapted to be mounted in the burner wall of a combustion chamber. 